Amputation bone cap

ABSTRACT

A muscle fastening cap includes a head having one or more groups of openings along a direction of its axial length. The cap also may include a stem adapted for insertion into a muscle-supporting structure such as an intramedullary canal or a prosthesis device.

FIELD OF THE INVENTION

The invention relates to a fastening cap for attaching muscles, and moreparticularly to a cap for terminating a bone or prosthesis device andfastening muscles and as a device to close off the intramedullary canalof a bone following amputation and/or to extend the length of theremaining bone stump.

BACKGROUND

General, vascular and plastic surgeons perform between 185,000 to200,000 amputations each year in the United States on patients of allages, including military personnel, as well as civilian children,adults, and the elderly. Several apparatuses and techniques are used bysurgeons to control pain and prevent post-operative bleeding associatedwith these procedures and to enable the implementation of prostheticfittings. For example, a bone cap can be used to cover the exposed endof an excised bone to limit bone overgrowth that can potentially lead tofriction and pressure on the surrounding muscle and limb. There is nodevice to date, that can provide the attachment and balancing of theadjacent transected muscles to attach to the bone stump in order toadjust and to balance the muscle tension of the remaining muscles toavoid the well known problem of stump contractures which often occursfollowing amputation of various bones at different anatomic levels ofamputation.

SUMMARY

In one aspect of the invention, a muscle fastening cap includes a headincluding one or more groups of openings for attaching at least onemuscle along a direction of its axial length. The head also includes asecond portion for providing a stem that connects to a muscle-supportingstructure. The muscle fastening cap also includes a stem extending fromthe second portion of the head. The stem is adapted for insertion into amuscle-supporting structure.

In another aspect of the invention, a modular muscle-fastening systemincludes a first portion and a stem portion which extends from the firstportion. The first portion includes at least one group of holessubstantially aligned along a first direction. The stem portion isconfigured to mate with a member of a prosthesis device to provide amechanical connection between the stem portion and the prosthesisdevice.

In yet another aspect of this invention, a method of fastening a modularmuscle of an amputee includes providing a muscle cap having a firstportion and a second portion, the first portion includes at least onegroup of through holes substantially aligned along a first direction andthe second portion forming a stem extending from the first portion inthe first direction. The stem portion is positioned in themuscle-supporting structure and a plurality of surgical tapes is passedthrough the respective through holes formed in the first portion. Thesurgical tapes are then secured to adjacent muscle tissue.

Additional aspects and advantages of the invention will be set forth inthe description that follows, and in part will be apparent from thedescription, or may be learned from practice of the invention. Theaspects and advantages of the invention will be realized and attained bythe system and method particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and exemplary only andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding and are incorporated in and constitute a part of thisspecification, illustrate embodiments of the invention that togetherwith the description serve to explain the principles of the invention.In the drawings:

FIGS. 1A and 1B are diagrams respectively showing front and side viewsof an exemplary muscle fastening cap according to some embodiments.

FIG. 2 is a diagram of an exemplary muscle fastening cap coupled to abone canal.

FIG. 3A is a diagram of an exemplary muscle fastening cap for use inmodular assemblies.

FIG. 3B is a diagram of an exemplary muscle fastening cap coupled to aprosthetic according to an exemplary modular assembly.

FIGS. 4A, 4B, 4C, and 4D are diagrams of various types of stems that canbe inserted into a bone canal.

FIG. 5 is a diagram showing an exemplary muscle fastening cap attachedto a muscle.

DETAILED DESCRIPTION

FIGS. 1A and 1B respectively show a front and side view of an exemplaryfastening cap 100 according to some embodiments attachable to amuscle-supporting structure, such as a bone or a prosthesis device. Thefastening cap 100 may be made from any biocompatible material, such ascobalt chrome or titanium, although other biocompatible metal alloys,composites or materials may be used. With reference first to FIG. 1A, afastening cap 100 includes a rounded head 110 and openings 120 a to 120d, and 130 a to 130 d on opposing sides of the head 110 and along thedirection of axis 102. The head 510 may be of a varying length and avarying diameter. The head 510 may also be of varying shape, such ashemispherical or conical, for example. While FIG. 1 shows four openingsalong two sides of the fastening cap 100, more or fewer holes may beincluded on the head 110 along a greater or smaller number of sides.

As shown in FIG. 1A, the fastening cap 100 may be provided with twoskirt portions 140 a and 140 b that extend further than the rest of thehead and are arranged to receive a stem 150, which may be adapted forattachment to a muscle-supporting structure, such as a canal of ahollowed out bone or to a prosthesis device, for example. FIG. 1B showsthe fastening cap 100 of FIG. 1A rotated 90 degrees to show that theopenings 120 a to 120 d and 130 a to 130 d can extend through the head110, although only the openings 120 a to 120 d and one skirt portion 140a are shown for clarity of illustration. The head 110 can be attached tothe stem 150 by any of a variety of known ways. For example, the head110 and stem 150 can be fit together with a taper, such as a Morse taperalthough other methods of mechanically connecting the head to the stemcan be used. For instance, the head 110 can be inserted into the stem150 and twisted into place. In other embodiments, the head and stem cancomprise a single part. FIG. 2 shows an exemplary embodiment of a musclefastening cap 200 including a head 210 and openings 220 a to 220 c, and230 a to 230 c. The head 210 is connected to a stem 235 that can beinserted into an intramedullary canal 260 of a partially hollowed outbone 240. For example, marrow from the intramedullary canal of a bonecan be removed from the excised end 242 of the bone 240. The stem 235can be fixed in place in the bone canal 260 by impaction, or by abiocompatible adhesive such as polymethylmethacrylate (PMMA). The stem235 can be of a varying length and a varying diameter, depending on thekind of bone and the size of intramedullary canal 260 into which thestem 235 is being inserted. For example, a stem of a muscle fasteningcap to be inserted into a femur may have a longer length and largerdiameter than a stem of a muscle fastening cap to be inserted into ahumerus.

FIG. 3A depicts a muscle fastening cap according to some embodiments,that includes a first portion 310, a group of through holes 320 a to 320c and a group of through holes 330 a to 330 c aligned in the directionof elongation of the first portion 310. A second portion 312 joins acentral portion 332, which in turn joins a stem portion 335.

The stem 335 can be a variety of shapes and sizes and can have a varietyof surfaces to join to a muscle-supporting structure such as a bonecanal or a modular prosthesis. For example, FIG. 4A shows a stem 410featuring a tapered end where sides 412 a and 412 b approach one anotherat one end to enable a taper connection with another prosthesis piece(e.g., a Morse taper fit). The tapered end can also provide a frictionfit into the intramedullary canal. A stem can also have a rough ortextured surface or fluted edges to better engage the muscle fasteningcap to a bone or bone-like structure. For example, FIG. 4B is a diagramof a stem 420 featuring threads 422 a to 422 d which can urge the stemmore securely into an intramedullary canal and/or fasten the stem toanother modular-type prosthesis piece. FIG. 4C shows bumps orprotrusions 432 a to 432 e on the surface of a stem 430 and FIG. 4Dshows a series of ridges or ribs 442 a to 442 c along a stem 440.Although not shown, the stem can also comprise a flange with sharpenededges. Such anchoring mechanisms may be included individually or in anycombination to promote better integration of a stem with anintramedullary canal or to a modular prosthesis piece, or another kindof fitting may be used.

The cap and stem of FIG. 3A may be a unit within a system of orthopedicmodularity. Referring now to FIG. 3B, a muscle fastening cap such as theone shown in FIG. 3A is a unit of a modular system which can include amodular prosthesis 360. The muscle fastening cap with the first portion310, the group of through holes 320 a to 320 c, the second portion 312,and the central portion 332 can be inserted into the modular prosthesis360 via connection with the stem portion 335. For example, theconnection between the stem portion 335 and the modular prosthesis 360can be provided with a taper fit. This can provide a multi-jointprosthesis, including a tapered stem that can prevent sliding movementof the prosthesis into the intramedullary passageway of a bone. Amulti-joint modular prosthesis 360, including a connection point 370 anda ball module 380 is shown in FIG. 3B. However, a modular prosthesis caninclude only a single piece or be a highly complex prosthetic device.The prosthesis may be an internal prosthesis, for example, an artificialhip joint or other kind of artificial joint. Additionally, theprosthesis may also be an external prosthesis, providing an artificialleg or other kind of artificial limb.

FIG. 5 shows a muscle fastening cap 500, having a head 510 and a groupof openings 520 a to 520 d. The cap 500 is inserted into anintramedullary canal 540 of a partially hollowed out bone 560 via a stemportion 545. A muscle 550 that surrounds the bone 560 may be anchored tothe head 510 by passing surgical tapes 530 a to 530 d through the muscle550 located around the bone 560 and through the openings 520 a to 520 dprovided in the head 510. This tape could be, for example, Dacron tapeor another kind of biocompatible suture. The tension in the tapes 530 ato 530 d can be adjusted to provide a suitable attachment of the muscle550 to the head 510. The surgical tapes can then be secured with asurgical knot to anchor the muscle 550 to the head 510.

The bone 560 can be, for example, the distal end of a residual limb. Aresidual limb can be created through a disarticulation across one of thefollowing: the humerus (above the elbow), the radius (below the elbow),the femur (above the knee), or the tibia (below the knee) and anexemplary fastening cap could be used in any of the related residuallimbs. The tapes can be attached to the holes in the head 510 as well asthe major muscle groups of the limb. For example, adductors, thehamstrings, and the quadriceps of the thigh can be attached to the head510 of the muscle fastening cap for an above the knee amputation.However, there could be a greater or smaller number of muscles attachedto the muscle-supporting structure.

Attachment of the muscles to a muscle fastening cap via surgical tapes,as described in embodiments herein, can prevent contractures (i.e.,irreversible muscle contraction or shortening that occur over time as aresult of unnatural stress on the limb). Additionally, by stabilizingthe tissue surrounding the distal limb, bursas can be prevented fromdeveloping at an amputation tip, which reduces pain and discomfort. Amuscle fastening cap, as described herein, also can also provide a capfor overgrowth of an excised bone, for example a cap for bone overgrowthin amputations performed on children and adolescents. Therefore,implementing a muscle fastening cap described herein can provide ways todecrease pain, and retain flexibility and mobility for amputees of allages.

U.S. Pat. No. 7,374,577 describes an implant device including a platethat is adapted for insertion into an intramedullary canal and has aplurality of muscle fixing holes dispersed on the plate. While thesemuscle fixing holes can be used to secure the muscle, the length anddiameter of the plate is generally fixed to that required to adequatelycap the bone. More particularly, this device is applied to a legamputation, as a load bearing device to improve ease of walking with aleg prosthesis. By contrast, the muscle fastening cap described hereincan be incorporated in a variety of limbs. The muscle fastening capdescribed herein can also vary in length to increase the overall lengthof an excised bone, permitting improved fitting, greater comfort, andmobility for a prosthesis device. This is especially useful for youngerpatients with smaller limbs or other patients with shorter distal limbsthat would benefit from being lengthened.

The muscle fastening cap can be conveniently used by general, vascularand plastic surgeons as well as orthopedic surgeons because it wouldrequire little or no instrumentation to enable insertion, and can beeasily and conveniently stored as individual parts that can be fittogether as required. This muscle fastening cap provides an improvementover the previous method of suturing distal muscles directly to theresidual bone, which can weaken the bone and provide unreliableconnection points with the muscle groups. Further, because the musclefastening cap is inserted into the intramedullary canal, pain andpostoperative bleeding that result from an excised limb can be reducedor prevented by capping the excised bone. The muscle fastening cap canprevent bleeding by functioning as a cork within the bone. The cap canalso reduce post-operative pain as well as phantom pain syndromes byclosing the open canal, similar to the pain relief provided by a fillingin a tooth cavity. It will be apparent to those skilled in the art thatvarious changes and modifications can be made in the method and systemfor accumulating and presenting device capability information of thepresent invention without departing from the spirit and scope thereof.Thus, it is intended that the invention cover the modifications of thisinvention provided they come within the scope of the appended claims andtheir equivalents.

What is claimed is:
 1. A method of fastening a modular muscle of anamputee, comprising: providing a muscle cap having a first portion and asecond portion, the first portion extending in a first direction,including at least one group of through holes substantially alignedalong the first direction where each of the through holes extends in asecond direction transverse to the first direction and the secondportion forming a stem extending from the first portion in the firstdirection, positioning the stem portion in a muscle-supporting structuresuch that said first portion is exposed in relation to themuscle-supporting structure; passing a plurality of surgical tapesthrough respective through holes formed in said first portion, andsecuring said surgical tapes to adjacent muscle tissue.
 2. The method ofclaim 1, wherein the stem comprises a tapered surface.
 3. The method ofclaim 1, wherein each through hole is configured to receive at least oneof said plurality of surgical tapes for securing muscle tissue to thefirst portion.
 4. The method of claim 1, wherein the first portion andsecond portion are integrally formed with one another.
 5. The method ofclaim 1, wherein the first portion has a hemispherical shape.
 6. Themethod of claim 1, wherein the first portion has a conical shape.
 7. Themethod of claim 1, wherein said stem portion is inserted into a bonecanal.
 8. A method of fastening a modular muscle of an amputee,comprising: providing a muscle cap having a first portion and a secondportion, the first portion extending in a first direction, including atleast one group of through holes substantially aligned along the firstdirection where each of the through holes extends in a second directionsubstantially perpendicular to the first direction and the secondportion forming a stem extending from the first portion in the firstdirection, positioning the stem portion in a muscle-supporting structuresuch that said first portion is exposed in relation to themuscle-supporting structure; passing a plurality of surgical tapesthrough respective through holes formed in said first portion, andsecuring said surgical tapes to adjacent muscle tissue.